1. Field of the Invention
The present invention relates to methods for limiting human exposure to the ionizing and electromagnetic fields emanating from a television receiver and more particularly pertains to a television receiver viewing distance sensor switch which may be utilized for reducing or eliminating radiative emissions from a television receiver when potential viewers are positioned within a preset range.
2. Description of the Prior Art
The use of devices to limit human exposure of television receiver radiation is known in the prior art. More specifically, television receiver radiation exposure limiting apparatus heretofore devised and utilized for the purpose of reducing human exposure of ionizing and electromagnetic radiation emissions are known to consist basically of familiar, expected and obvious structural configurations, notwithstanding the myriad of designs encompassed by the crowded prior art which have been developed for the fulfillment of countless objectives and requirements.
For example, U.S. Pat. No. 4,417,278 to Hensleigh et al discloses a television receiver scrambling system wherein a sensor actuated radio frequency transmitter is employed to disrupt the video and audio portions of any proximate television receiver whenever a human form approaches within a preset range of the sensor device. Sensors disclosed in the Hensleigh invention include an acoustic transducer and a tuned pickup coil, and furthermore there exists no hardwire link between the television scrambling system and the television receiver. The present invention employs a sensor actuated device which removes incoming information signals from the television receiver using a hardwire ling thereby obviating the requirement for additional electromagnetic radiation whenever a preset range is encroached therein.
In U.S. Pat. No. 4,835,614 to Ryu a control method for limiting watching distance in television is disclosed. The Ryu invention comprises the algorithm required to preclude interference of infrared signals from a remote control transmitter and a watch-distance-limit-device. The present invention discloses, in the language of the Ryu invention a watch-distance-limit-device and is not associated with algorithm requirements.
In U.S. Pat. No. 4,321,593 to Ho et al. a television set with supervisory functions of alarming burglary and safe watching distance is described. The Ho et al. apparatus is necessarily a complex electronic assembly comprising a moving target type sensor, a signal processor, an indication or alarm, a means for removing power from an interconnected television receiver, a power supply for both external and internal electronic controls, and an interconnection to the detected video or intermediate frequency channel of the television receiver to provide video blanking. Installation of the Ho et al. apparatus requires access to the interior workings of the television receiver and is likely to be performable by only qualified service personnel. The present invention is a remarkably simple device which may be installed by unscrewing the external lead wire or coaxial cable Ultra High Frequency/Very High Frequency (UHF/VHF) signal input to the television receiver and introducing a threaded mating component in a series relationship with the UHF/VHF signal input and the television receiver. Additionally, the present invention does not inject video blanking signals at the intermediated frequency or the video channel of the television receiver, a simple disconnect of the UHF/VHF signal input is described in the preferred embodiment, however an alternate embodiment introduces a video blanking signal at the UHF/VHF signal input terminals. The present invention requires no access or connections to the internal portion of the television receiver and therefore is suited for safe and proper installation by untrained personnel. And furthermore, the present invention employs a proximity sensor not requiring motion to generate an alarm signal.
In U.S. Pat. No. 4,835,614 to Kim et al. a circuit for eyesight protection in a television set is disclosed. The Kin et al. circuit comprises an infrared optical transmitter, an infrared optical receiver, and an internal interconnection to the video amplifier portion of the attached television receiver. Should a human form approach within a preset detection range, pulsed infrared radiation from the transmitter having been reflected from the human form and exceeding a particular amplitude and time threshold at the receiver, forces deactivation of the video amplifier section of the interconnected television receiver thereby blanking the screen. The Kim et al. patent is directed toward limiting viewing distance from a television receiver for the worthy purposed of maintaining viewer eyesight. The present invention does not require a pulsed transmitter for operation and has no interconnections internal to the television receiver.
In U.S. Pat. No. 4,831,448 to Park a viewing distance sensor for television receiver is disclosed. The Park invention comprises a monostatic infrared proximity sensor designed to operate without mutual optical interference with any other electronic control device operating in the area. A disadvantage in this prior art lies in a requirement for an internal interconnection of the sensor to the portion of the television receiver circuit which generates the image signal and the requirement for a transmitter and receiver. The present invention does not require any internal link with television receiver components and furthermore prefers a simpler passive infrared proximity sensor.
As illustrated by the background art, efforts are continuously being made to attempt to improve the state-of-the-art of devices limiting the proximity of human viewers of television receivers. No prior effort, however, provides the benefits attendant with the present invention. Additionally, the prior patents and commercial techniques do not suggest the present inventive combination of component elements arranged and configured as disclosed and claimed herein.
Therefore, it can be appreciated that there exists a continuing need for television receiver viewing distance sensor switch which can be employed to provide safe viewing of television programming by the general population. In this regard, the present invention substantially fulfills this need.
The present invention achieves its intended purposes, objects, and advantages through a new, useful and unobvious combination of method steps and component elements, with the use of a minimum number of functioning parts, at a reasonable cost to manufacture, and by employing only readily available materials.